Defect Engineering of GaN Epi-Layers by Irradiation with Electrons and Post Thermal Annealing

Abstract

Deep level transient spectroscopy (DLTS) was used to investigate the electrical properties of GaN irradiated by high-energy electrons. The GaN epi-layers were grown on sapphire substrates by using metal-organic chemical-vapor deposition (MOCVD). The electron irradiations were done by 2-MeV energy beam with a 1 x 10(15) cm(-2) dose and the post thermal annealing was processed in a nitrogen atmosphere for 60 s. In the DLTS measurement, the as-irradiated GaN sample showed four different peaks, but those peaks were partially reduced and eliminated after annealing at 700 degrees C. After annealing at 900 degrees C, the crystallinity of the electron-irradiated GaN was remarkably improved and was as good as that of the as-grown GaN epi-layer. This showed that the electron-irradiation and post-thermal-annealing methods could be useful tool for controling of defects in GaN epi-layers.